Is it intended behavior that soft deletions are not respected by default in (morph) many-to-many relationships with a pivot table?

[Azeirah]

I have a ManyToMany relationship between Upsell Pages and Products. The intermediate (morph) table is "upsell_products".

class UpsellPage extends Model {
  ...
  public function products(): MorphToMany
  {
    return $this->morphToMany(product::class, name: "upsell_configurable", table: "upsell_products")
      ->using(UpsellProduct::class)
      ->wherePivotNull("deleted_at")
      ->withPivot(["options", "sort_key"]);
  }
}

My UpsellProduct MorphPivot looks like this, it is very basic. Of note is the "use SoftDeletes" line:

class UpsellProduct extends MorphPivot
{
  use SoftDeletes;

  protected $table = "upsell_products";

  protected $fillable = ["sort_key", "product_id"];

  public function upsell_configurable(): MorphTo
  {
    return $this->morphTo();
  }
}

Normally, I'd expect Laravel to ignore models that are soft deleted. For example, if I had just a regular HasMany relationship with products, retrieving a list of products like so

// the query has where deleted_at = null
$upsellPage = UpsellPage::find($upsellPageId)->products;

But in the case of the ManyToMany with a pivot, this is not the case. I have to explicitly add the ->wherePivotNul("deleted_at") in the MorphToMany relationship.

Is this an intentional design decision? If so, can I read about why this decision was made?

And secondly, is there a reason why there is no "wherePivotTrashed" and it's sibling method "wherePivotNotThrashed" methods for pivot relationships? I find it strange that I have to use ->wherePivotNull('deleted_at'), when I'd expect ->wherePivotNotThrashed